By PERRY NODELMAN

he artist in the apartment upstairs befriends a young boy but won't allow the boy to see what he's painting. When the artist takes a trip and leaves the boy his keys, the boy finds the finished pictures standing against the wall, each accompanied by a message for him. This slight story is mostly a subterfuge, a way of accounting for the full-page images of the paintings that are the core of ''The Collector of Moments.''

This book resembles Chris Van Allsburg's groundbreaking 1984 picture book, ''The Mysteries of Harris Burdick,'' which also consists of a slight framing story that justifies a series of disconnected pictures, each with a brief and mysterious caption inviting viewers to imagine the events the picture shows. The German illustrator and author Quint Buchholz's muted color pictures are also similar in style to Van Allsburg's stark black-and-white ones in ''Harris Burdick.'' Both illustrators offer carefully detailed, almost photographic representations that contain surrealistic details: in ''Harris Burdick'' a wallpaper bird beginning to take flight or a floating nun, in ''The Collector of Moments'' a gift package as big as a house or a floating circus wagon.

Although it may seem familiar in conceit, ''The Collector of Moments'' is beautiful and fascinating, a pleasure to look at. The design establishes a quirky but intriguing rhythm as it moves irregularly between pages dominated by large color images and pages that are mostly words, accompanied by small sepia images. The images themselves precisely evoke mysterious possibilities with a satisfyingly dreamy melancholy. Edward Hopper might have painted them after taking a few lessons from Rene Magritte.

The painter of the story calls himself, in Peter F. Neumeyer's smooth translation, a ''collector.'' ''I collect moments,'' he explains. But, the boy says as he gazes at the artist's paintings, ''I understood that there was always a story attached to this moment which had begun long before and would continue long afterward.'' Just as the artist did for the boy with his mysterious messages, Buchholz cleverly encourages viewers to discover the stories attached to his pictures. The mysterious messages point to possibilities that the boy himself claims to imagine but never tells us about, so that we have to reimagine them for ourselves.

The unexpected details in the pictures demand equally imaginative acts of explanation. In addition, Buchholz often shows people looking at objects behind walls or through doors or even beyond the frame of the paintings -- objects that viewers can't literally see and must therefore envisage for themselves.

As the creator of images most interesting for what they don't in fact show, Buchholz is himself an accomplished collector of moments. Not only does his book tell young readers things worth knowing about how to look at pictures, but the pictures themselves delightfully repay the kind of attention they invite viewers to give them.

Perry Nodelman's most recent book is the young-adult fantasy ''A Meeting of Minds.''